Resin coated sand (RCS) with phenolic resin matrix can hardly be collapsed when it is used in Al-alloy casting. Adding collapsing agent and reducing the concentration of resin are solutions adopted by workers, but the...Resin coated sand (RCS) with phenolic resin matrix can hardly be collapsed when it is used in Al-alloy casting. Adding collapsing agent and reducing the concentration of resin are solutions adopted by workers, but these methods tend to reduce the initial strength of RCS. Synthesis of modified phenolic resin with direct-chain diacid DAn (/JS=6, where n means carbon amount) was studied here. The effects of the addition of modifying agent on molecular weight, gel time and softening point were investigated. Optimal addition of DAn (10% phenol) was obtained by testing the initial and retained flexural strengths of the modified resin. FT-IR spectra showed that carbonyl shifts to higher wave number. With the use of TG, SEM and strength loss curves, the relation between initial and retained strengths was analysed. Tests on the heated deformation curve, before and after resin modification, show that PF-DA10 has the characteristic of higher initial and retained strengths together.展开更多
针对不规则区域面积测算中定位精度和面积计算精度两方面不足,提出一种定位精度高、面积误差小的面积测算新方法。其采用一种组合定位方法精确定位,即将差分GPS测量系统(DGPS)与马尔可夫链蒙特卡罗(Markov chain Monte Carol,MCMC)粒子...针对不规则区域面积测算中定位精度和面积计算精度两方面不足,提出一种定位精度高、面积误差小的面积测算新方法。其采用一种组合定位方法精确定位,即将差分GPS测量系统(DGPS)与马尔可夫链蒙特卡罗(Markov chain Monte Carol,MCMC)粒子滤波相结合,再配合复化Newton-cotes算法,拟合边界曲线并准确求得区域面积。将MCMC粒子滤波应用于DGPS定位数据处理,其既可处理非高斯分布噪声,又解决粒子滤波(PF)的粒子退化问题,提高定位精度。将复化Newton-cotes算法应用于面积计算,其既避免高次插值的舍入误差,又将面积区间进一步细分,提高面积计算精度。实验结果表明,该新方法定位精度更高,面积误差更小。展开更多
文摘Resin coated sand (RCS) with phenolic resin matrix can hardly be collapsed when it is used in Al-alloy casting. Adding collapsing agent and reducing the concentration of resin are solutions adopted by workers, but these methods tend to reduce the initial strength of RCS. Synthesis of modified phenolic resin with direct-chain diacid DAn (/JS=6, where n means carbon amount) was studied here. The effects of the addition of modifying agent on molecular weight, gel time and softening point were investigated. Optimal addition of DAn (10% phenol) was obtained by testing the initial and retained flexural strengths of the modified resin. FT-IR spectra showed that carbonyl shifts to higher wave number. With the use of TG, SEM and strength loss curves, the relation between initial and retained strengths was analysed. Tests on the heated deformation curve, before and after resin modification, show that PF-DA10 has the characteristic of higher initial and retained strengths together.
文摘针对不规则区域面积测算中定位精度和面积计算精度两方面不足,提出一种定位精度高、面积误差小的面积测算新方法。其采用一种组合定位方法精确定位,即将差分GPS测量系统(DGPS)与马尔可夫链蒙特卡罗(Markov chain Monte Carol,MCMC)粒子滤波相结合,再配合复化Newton-cotes算法,拟合边界曲线并准确求得区域面积。将MCMC粒子滤波应用于DGPS定位数据处理,其既可处理非高斯分布噪声,又解决粒子滤波(PF)的粒子退化问题,提高定位精度。将复化Newton-cotes算法应用于面积计算,其既避免高次插值的舍入误差,又将面积区间进一步细分,提高面积计算精度。实验结果表明,该新方法定位精度更高,面积误差更小。
